After the January 2010 earthquake in Haiti, an existing development program promoting household water treatment with chlorine rapidly expanded and provided relief to 15,000 earthquake-affected households. Initially, 157 community health workers (CHWs) distributed chlorine tablets; ten months later, CHWs began selling locally manufactured solution. The program was externally evaluated in March and November 2010; 77–90% of recipients had free chlorine residual (FCR) in household water. Internal monitoring by three supervisors and 157 CHWs also began in 2010. We analyzed results from 9,832 supervisor and 80,371 CHW monitoring visits conducted between 2010 and 2014 to assess: whether success continued in the rehabilitation phase; internal data validity; and factors impacting adoption. In 2010, 72.7% of supervisor visits documented total chlorine residual (TCR) comparable to external evaluation results. TCR presence was associated with certain supervisors/CHWs, earlier program year and month (in 2014, supervisor visits TCR presence dropped to 52.1%), living in plains (not mountainous) regions, and certain calendar months. CHW visits recorded 18.1% higher TCR presence than supervisor visits, indicating bias. Our results document a program with sustained (although slightly declining) household chlorination use, provide insight into validity in internal monitoring, and inform discussions on the value of linking successful development programs to emergency relief, rehabilitation, and development.